tonyfettes/ghostty

A MoonBit translation of the Ghostty terminal parser stack and terminal surface.

This repository is not a Ghostty frontend. It focuses on the terminal parsing, state, formatting, input encoding, and host-facing terminal APIs that sit behind Ghostty's UI. The upstream source of truth is vendored as a submodule under upstream/ghostty, and the translation plan is tracked in docs/.

Scope

The current project goal is a faithful MoonBit translation of Ghostty's parser and terminal model layers:

• DEC ANSI parser state machine and parse table
• UTF-8 stream handling with Ghostty-compatible retry/replacement behavior
• CSI, OSC, DCS, SGR, and related semantic decoders
• StreamTerminal terminal state application
• formatter/render-state helpers for plain, VT, and HTML output
• input encoders, mouse helpers, selections, colors, palette state, and Kitty graphics metadata needed by the terminal surface

Out of scope for now:

• GTK, macOS, or other Ghostty frontend code
• native C ABI/export parity
• full PTY/runtime integration beyond examples and host callbacks
• packaging a complete terminal emulator application

For the detailed upstream-to-MoonBit architecture, read docs/architecture.md. For a map of how the terminal package and its sub-packages are organized (what lives where and how to read it), see docs/terminal-package.md. For the execution plan and quality gates, read docs/plan.md.

Package

The main public package is:

tonyfettes/ghostty/terminal

In a MoonBit package, import it from moon.pkg:

import {
  "tonyfettes/ghostty/terminal"
  "moonbitlang/core/encoding/utf8"
}

Minimal usage:

///|
fn render_plain(input : Bytes) -> String {
  let terminal = @terminal.StreamTerminal::new()
  ignore(terminal.resize(80, 24, 8U, 16U))
  terminal.next_slice(input)
  let formatter = @terminal.Formatter::new_terminal(
    terminal,
    @terminal.FormatterOptions::new(
      Plain,
      trim=true,
      extra=@terminal.FormatterTerminalExtra::none(),
    ),
  )
  @utf8.decode_lossy(formatter.format())
}

The generated public interface lives at terminal/pkg.generated.mbti.

Repository Layout

terminal/                      MoonBit terminal parser and model package
docs/architecture.md           Parser stack architecture notes
docs/plan.md                   Translation plan, scope, and quality gates
docs/plans/                    Task-specific implementation plans and audits
examples/rabbita_asciinema/    Browser asciinema player using StreamTerminal
examples/terminal_playground/  Browser terminal playground (web shell + wasm-gc core/)
examples/tmux/                 Native mini tmux-like PTY multiplexer demo
bench/                         StreamTerminal benchmarks (moon bench) + per-workload profiling mains
upstream/ghostty/              Upstream Ghostty submodule

Development

Install MoonBit, then from the repository root run the core validation commands:

moon check --target native
moon test --target native
moon check --target js
moon test --target js
moon coverage analyze -- -f summary
moon fmt
moon info

The examples live in a separate MoonBit module under examples/ and contain mixed target packages. Use explicit targets:

moon -C examples check --target js
moon -C examples test --target js
moon -C examples check --target native
moon -C examples test --target native

Examples

• Rabbita asciinema player
• Mini tmux PTY demo

Translation Notes

The translation is intentionally conservative:

• parser state transitions stay table-driven
• Parser.next action ordering is preserved
• OSC and DCS parsing remain separate semantic layers
• terminal state and host callbacks are kept distinct
• public MoonBit APIs are reviewed through generated .mbti files

When changing MoonBit source, run the validation commands above and review any generated interface churn before committing.

License

This repository is licensed under Apache-2.0. The upstream Ghostty source under upstream/ghostty is a submodule; consult that project for its own license and source history.